CN104062502B - A kind of cross interconnected system phase inspection method of high-tension cable - Google Patents

Abstract

The invention discloses a phase inspection method of a high-voltage cable cross-interconnection system. The method includes: inspectors perform wiring at the first section of the high-voltage cable; Go to the No. 2 joint box of the high-voltage cable to check the phase of the cross-connection system; repeat the above steps until the phase inspection of all cross-connection systems is completed. The method of the invention improves the phase inspection method of the previous high-voltage cable cross-connection system, and can quickly and efficiently complete the phase inspection work only through an ordinary multimeter and simple wiring under the condition that no one at the opposite end cooperates.

Description

A phase inspection method for high-voltage cable cross-connection system

technical field

The invention relates to a voltage phase measuring device, in particular to a phase checking method of a high-voltage cable cross-connection system.

Background technique

Due to its excellent electrical properties, good heat resistance, and the advantages of convenient laying and accessories installation and no drop restrictions, high-voltage XLPE cables also consider the requirements of municipal planning and the main network frame of urban and development areas. Overhead lines are gradually being replaced by high voltage cables.

Due to the high voltage level and large flow capacity, the high-voltage XLPE cables are all single-core cables. The relationship between the conductor of the single-core cable and the metal sheath is equivalent to the primary winding and the secondary winding of the transformer. When the cable conductor flows through the AC current, an induced voltage will be generated in the metal sheath, so the metal sheath of the single-core cable The connection method has an important influence on the carrying capacity and safe and stable operation of the high-voltage cable.

The cross-connection system of high-voltage cables is a system composed of connecting the metal sheaths of long-distance high-voltage single-core cables according to certain rules, and the phase inspection of the cross-connection system is one of the field handover test items of high-voltage cables.

Contents of the invention

The purpose of the present invention is to provide a phase inspection method for a high-voltage cable cross-connection system, which aims to solve the inconvenience caused by the need for technicians to cooperate at the opposite end when performing phase inspection in the prior art. The method of the invention only needs to connect the three-phase metal sheaths in the manners of direct grounding, resistance grounding and non-grounding respectively, and the detection personnel can complete the phase inspection work at the other end.

Innovation point: the present invention can check the cross-connection system of high-voltage cables only through an ordinary multimeter and simple wiring, without the cooperation of any personnel

The present invention is realized in this way. A phase inspection method of a high-voltage cable cross-connection system includes: Step 1: The inspector performs wiring at the first section of the high-voltage cable; Step 2: The inspector goes to the No. 1 joint box of the high-voltage cable to the cross-connection system Conduct phase inspection; Step 3: inspectors go to the No. 2 joint box of the high-voltage cable to perform phase inspection on the cross-connection system; Step 4: Repeat the above steps until the phase inspection of all cross-connection systems is completed.

Step 1: First, inspectors perform wiring on the first section of the high-voltage cable. Phase a of the metal sheath is directly grounded, phase b is grounded through a 100 ohm resistor, and phase c is suspended without grounding.

Step 2: inspectors go to the No. 1 joint box of the high-voltage cable to check the phase of the cross-connection system. At the joint box No. 1, the metal sheaths of the two sections of cables will be led out to the cross-connection box through the coaxial cable during the construction of the cable joint, so there will be 6 phases, that is, 3 phases of the inner core and 3 phases of the outer core of the coaxial cable. Use the resistance (ohm) file of the multimeter to measure the inner and outer cores of the coaxial cable respectively to the ground. At this time, the resistance of zero is the a phase of the cable head end, the resistance of about 100 ohms is b phase, and the resistance of c phase is infinite. The resistance of the remaining three-phase wire cores (a1, b1, c1) is also infinite, and the three-phase wire cores point to the No. 2 joint box. Then, directly ground the a1 phase of the metal sheath, ground the b1 phase through a 100 ohm resistance, and leave the c1 phase suspended without grounding to prepare for the next step of phase inspection.

Step 3: The inspector goes to the No. 2 joint box of the high-voltage cable to check the phase of the cross-connection system. Repeat the second step to check the content to ensure that the phases of a1, b1, and c1 of the No. 2 joint box are correct and point to the No. 1 joint box. Then prepare the metal sheaths of phases a2, b2, and c2 for phase inspection, and go to the No. 3 joint box for inspection.

Step 4: Repeat the above steps until the phase inspection work of all cross-connection systems is completed.

The cross interconnection system is to divide the cable line into several large sections, and each large section is divided into three small sections of equal length in principle. Insulated joints are installed between each section, and the three phases of the metal sheath at the insulating joints are crossed by coaxial cables. Interconnection, a set of overvoltage protectors are installed at the insulating joints, and the metal sheaths at both ends of each large section are interconnected and grounded respectively.

A phase inspection method of a high-voltage cable cross-connection system according to the present invention. The present invention improves the phase inspection method of a high-voltage cable cross-connection system in the past. In the case of unmanned cooperation at the opposite end, only an ordinary multimeter and a simple Wiring, quickly and efficiently complete the phase inspection work.

Description of drawings

Fig. 1 is a schematic diagram of a high-voltage cable cross-connection system provided by an embodiment of the present invention;

Fig. 2 is a drawing of the coaxial cable provided by the embodiment of the present invention;

Fig. 3 is the actual wiring diagram of the cross interconnection box provided by the embodiment of the present invention;

Fig. 4 is a flowchart of an implementation method of a phase inspection method for a high-voltage cable cross-interconnection system provided by an embodiment of the present invention.

detailed description

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention, not to limit the present invention.

As shown in Figure 4, the present invention is implemented in this way. A phase inspection method for a high-voltage cable cross-connection system includes: step S401: the inspector performs wiring at the first section of the high-voltage cable; step S402: the inspector goes to No. 1 of the high-voltage cable The joint box checks the phase of the cross-interconnection system; step S403: inspectors go to the No. 2 joint box of the high-voltage cable to check the phase of the cross-interconnection system; step S404: repeat the above steps until the phase inspection of all cross-interconnection systems is completed.

As shown in Figure 1, the cross-connection system is mainly composed of multiple cross-connection boxes and wires;

Said step S401: first, inspectors perform wiring on the first section of the high-voltage cable. Phase a of the metal sheath is directly grounded, phase b is grounded through a 100 ohm resistor, and phase c is suspended without grounding.

The step S402: inspectors go to the No. 1 joint box of the high-voltage cable to check the phase of the cross-connection system. At the No. 1 joint box, the metal sheaths of the two sections of cables will be respectively led out (see Figure 2) to the cross-connection box (see Figure 3) through the coaxial cable during the construction of the cable joint, so there will be 6 phases, that is, the coaxial cable 3-phase inner core (upper part in Figure 3) and 3-phase outer core (lower part in Figure 3). Use the resistance (ohm) file of the multimeter to measure the inner and outer cores of the coaxial cable respectively to the ground. At this time, the resistance of zero is the a phase of the cable head end, the resistance of about 100 ohms is b phase, and the resistance of c phase is infinite. The resistance of the remaining three-phase wire cores (a1, b1, c1) is also infinite, and the three-phase wire cores point to the No. 2 joint box. Then, directly ground the a1 phase of the metal sheath, ground the b1 phase through a 100 ohm resistance, and leave the c1 phase suspended without grounding to prepare for the next step of phase inspection.

As shown in Figure 3, the cross interconnection box is mainly composed of: grounding terminal, sheath protector, inlet port, outer core holder, inner wire core holder nut; the ground terminal is installed on the upper right side of the cross interconnection box, and the inlet port is installed Below the cross interconnection box, the sheath protector is installed on the left side of the grounding terminal, the inner wire core holder nut is installed on the sheath protector, and the outer wire core holder is installed above the incoming line port.

The step S403: inspectors go to the No. 2 joint box of the high-voltage cable to check the phase of the cross-connection system. Repeat the second step to check the content to ensure that the phases of a1, b1, and c1 of the No. 2 joint box are correct and point to the No. 1 joint box. Then prepare the metal sheaths of phases a2, b2, and c2 for phase inspection, and go to the No. 3 joint box for inspection.

The step S404: repeating the above steps until the phase inspection work of all the cross-interconnection systems is completed.

Due to the high voltage level and large flow capacity, the high-voltage XLPE cables are all single-core cables.

The relationship between the conductor and the metal sheath of a single-core cable is equivalent to the primary winding and secondary winding of a transformer. When the cable conductor flows through the AC current, a part of the magnetic field lines generated around it will interlink with the metal sheath, and an induced voltage will be generated in the metal sheath. The magnitude of the induced voltage is not only related to the current flowing in the cable or the short-circuit current, but also related to the arrangement of the cable and the length of the cable line. If both ends of the metal sheath of the cable are grounded to form a closed path, a circulating current will be generated in the metal sheath; when the cable is in normal operation, the circulating current on the metal sheath and the load current of the wire are basically of the same order of magnitude, and a large circulating current will be generated The loss makes the cable heat up and affects the transmission capacity of the cable. Therefore, the connection method of the single-core cable metal sheath has an important impact on the current carrying capacity and safe and stable operation of the high-voltage cable.

In order to reduce the loss of the metal sheath and increase the transmission capacity of the cable, the metal sheath cross-connection can be used when the high-voltage cable line is long (more than 1km). As shown in Figure 1, the cross-interconnection system is to divide the cable line into several large sections. Coaxial cables are used for cross interconnection, a set of overvoltage protectors are installed at the insulating joints, and the metal sheaths at both ends of each large section are interconnected and grounded respectively.

The cross-connection system of high-voltage cables is a system composed of connecting the metal sheaths of long-distance high-voltage single-core cables according to certain rules.

Although the specific implementation of the present invention has been described above in conjunction with the accompanying drawings, it is not a limitation to the protection scope of the present invention. Those skilled in the art should understand that on the basis of the technical solution of the present invention, those skilled in the art do not need to pay any creative effort. Various modifications or deformations that can be made by labor are still within the protection scope of the present invention.

Claims (1)

1. A kind of 1. cross interconnected system phase inspection method of high-tension cable, it is characterised in that the cross interconnected system of the high-tension cable Phase shift inspection method includes：

   Step 1：Testing staff carries out wiring in the head end of high-tension cable；

   Step 2：Testing staff carries out phase shift inspection to No. 1 joint case of high-tension cable to cross interconnected system；

   Step 3：Testing staff carries out phase shift inspection to No. 2 joint casees of high-tension cable to cross interconnected system；

   Step 4：Above step is repeated, until completing the phase shift inspection work of all cross interconnected systems；

   Wiring is carried out for a phases of protective metal shell are directly grounded to the head end of high-tension cable in step 1, b phases are passed through into 100 Europe The resistance eutral grounding of nurse, c phases are hanging earth-free；

   The protective metal shell of two sections of cables is led to cross interconnected case by step 2 middle cable connector respectively by coaxial cable, that is, is connect Head case, measure the inside and outside core resistance of coaxial cable over the ground respectively, a phases, b phases and c phases of No. 1 joint case are determined, then by a Phase, the a1 phases of b phases and the corresponding No. 1 joint case of c, the protective metal shell of b1 phases and c1 phases carry out phase shift inspection preparation, are specially： A1 phases are directly grounded, and b1 phases pass through 100 ohm of resistance eutral grounding, and c1 phases are hanging earth-free；

   Cross interconnected case includes：Ground terminal, sheath protector, inlet wire port, outer core holder, interior core holder nut；Connect Ground terminal is arranged on the upper right side of cross interconnected case, and inlet wire port is arranged on the lower section of cross interconnected case, sheath protector installation In the left side of ground terminal, interior core holder nut is arranged on sheath protector, and outer core holder is arranged on inlet wire port Top；

   Content in repeat step two in step 3, to ensure to determine that a1, b1, c1 phase of No. 2 joint casees are correct, and point to No. 1 Joint case；A2, b2, c2 phase protective metal shell of No. 2 a1, b1, c1 corresponding joint casees are carried out into phase shift inspection again to prepare, gone to No. 3 joint casees are checked；

   One~step 3 of above step is repeated in step 4, until completing the phase shift inspection work of all cross interconnected systems；

   Cross interconnected system is that cable run is divided into some big sections, is divided into three segments of equal length again in principle per big section, Install insulating joint between every section, carried out with coaxial cable cross interconnected at insulating joint between protective metal shell three-phase, insulation connects One group of overvoltage protection device is installed at head, each big section of both ends protective metal shell interconnects ground connection respectively.